function Food(el){
    this.el=el
    this.len=20
    this.foodObj=null
    this.foodX=0
    this.foodY=0
}
Food.prototype.create=function(){
    let divObj=document.createElement('div')
    divObj.style.width=divObj.style.height=this.len+'px'
    divObj.style.backgroundColor='green'
    divObj.style.position='absolute'
    this.foodObj=divObj
    this.el.appendChild(divObj)
    this.move()
    

    
}
Food.prototype.move=function(){
    let foodXMax=this.el.clientWidth/this.len-1
    let foodYMax=this.el.clientHeight/this.len-1
    this.foodX=Math.floor(Math.random()*(foodXMax-0+1)+0)*this.len
    this.foodY=Math.floor(Math.random()*(foodYMax-0+1)+0)*this.len


     this.foodObj.style.left=this.foodX+'px'
     this.foodObj.style.top=this.foodY+'px'
}